EMag issue

[YellaDawg]

150 hours dual emags on IO390 in RV8. started with a "stumble" at low RPMs and not noticeable at higher RPMs, now noticeable. I think my left mag is not running internally. Here is my check:

Grounded the right mag at 1200 rpm, killed internal power on left mag and rpm went to zero and engine quit.
Grounded the left mag at 1200 rpm, killed internal power on right mag and rpm was steady and engine remained running.

My plan is to remove both mags for service. But at 150 hours???

I did a pull test on wires and all are attached, cleaned injectors, no change, plugs have 25 hours on them (issue started before new plugs)

Anything else I should check before I take them off?

 

[DanH]

Grounded the right mag at 1200 rpm, killed internal power on left mag and rpm went to zero and engine quit.

I'm confident you meant to write "killed external power". If you were conducting the test at typical RPM for the runup pad (1800 or so), then yes, your left internal generator is dead as canned tuna.

My plan is to remove both mags for service. But at 150 hours???

As noted elsewhere, self-powered is a great sales feature.

 

[Majorpayne317641]

Did you do the timing again?

If it dies during the run up check then yes that one is bad assuming your wiring is good.

 

[toolmanmike]

FwIW- my mags will not supply spark at 1200rpm. I need a bit more for full self exciting capability. Still seems like the left mag internal needs repaired.

 

[Majorpayne317641]

FwIW- my mags will not supply spark at 1200rpm. I need a bit more for full self exciting capability. Still seems like the left mag internal needs repaired.

That’s really high

 

[Carl Froehlich]

FwIW- my mags will not supply spark at 1200rpm. I need a bit more for full self exciting capability. Still seems like the left mag internal needs repaired.

My experince over 20 years with dual pMags. The internal generator will keep the fan running down to ~900 RPM or so. Your’s dies at 1200. Does it still work at 1500?

Working other pMag installs I’ll also note that for whatever reason builders get bent around the axle with their “test” switch, as in wiring mistakes when using a three position toggle switch. Same for using an old school Cessna key switch. I only use an on/off ignition toggle switches and pull-able breaker I suggest verifying wiring as the first step.

Side note - check that you grounded the pMags locally on the engine.

If after verify your symptoms the problem persists, contact eMag for repair.

Carl

 

[Rdog420]

Are these newer Emag’s with the “upgrade”? Or old bearings?

 

[Toobuilder]

I’ve had Pmags on several airplanes and they would self sustain to ~800 RPM as advertised. Much above that would indicate a problem to me.

 

[Rdog420]

I’ve had Pmags on several airplanes and they would self sustain to ~800 RPM as advertised. Much above that would indicate a problem to me.

The manual says that generator cut out tests will vary by engine, fuel system (carb vs injection) and other things.

 

[lr172]

The manual says that generator cut out tests will vary by engine, fuel system (carb vs injection) and other things.

How could the fuel system have any impact on what RPM the pmags generator is producing enough power to run the unit?

 

[Rdog420]

How could the fuel system have any impact on what RPM the pmags generator is producing enough power to run the unit?

Idk. Brad wrote the manual
It also says that they test open air spark down to 700 rpm.

 

[D-Dubya]

Sounds like ONE is bad...not sure why you'd want to pull both unless they need the bearing upgrade. Just because one failed at 150 hours doesn't mean the other is about to fail as well.